PC Electrical System Design & Installation 2

Question 1

When sizing a feeder for a commercial building with a calculated load of 180 amperes, what is the minimum conductor ampacity required per NEC Article 215?

Accepted Answer

180A

Answer

Feeder conductors must have an ampacity not less than the maximum load to be served, which is 180A per NEC 215.2(A)(1).

Question 2

Which NEC article governs the installation of electrical systems in hazardous (classified) locations?

Accepted Answer

Article 500

Answer

NEC Article 500 covers hazardous (classified) locations and defines the requirements for Class I, II, and III divisions.

Question 3

A 240V, single-phase motor nameplate shows 18A full-load current. What is the minimum branch circuit conductor ampacity required?

Accepted Answer

22.5A

Answer

Per NEC 430.22, branch circuit conductors for a single motor must have an ampacity of at least 125% of the motor's full-load current: 18A × 1.25 = 22.5A.

Question 4

When installing a panelboard in a bathroom of a dwelling unit, what does the NEC prohibit?

Accepted Answer

Panelboard installation entirely

Answer

NEC 240.24(E) prohibits overcurrent devices from being located in bathrooms of dwelling units, guest rooms, or guest suites.

Question 5

What is the maximum voltage drop recommended by the NEC for branch circuits serving lighting and receptacle outlets in a commercial installation?

Accepted Answer

3%

Answer

NEC 210.19(A) informational note recommends that the maximum voltage drop on branch circuits not exceed 3% for best performance.

(PC) Professional Electrical Contractor Practice Test

(PC) Professional Electrical Contractor Practice Test

PC Electrical System Design & Installation 2